Abstract：Objective To compare the biomechanical stability of different bisegment fixation methods for the lumbar spine.Methods Six adult cadaveric lumbar spines (L2-S1) were selected and fixed progressively with different fixation methods at L3/4-L4/5.The specimens were divided into five groups,Group A (normal specimen group),Group B (unilateral translaminar facet screw fixation + interbody cage fusion),Group C (unilateral pedicle screw fixation + interbody cage fusion),Group D (unilateral pedicle screw fixation combined with contralateral translaminar facet screw fixation + interbody cage fusion) and Group E (bilateral pedicle screw fixation + interbody cage fusion).After loading on the fixed segments in each group,range of motion (ROM),stability index,axial displacement as well as stiffness were measured and compared.Results Compared with normal specimen group,the four fixation modes reduced the ROM of L3/4-L4/5 in different directions and increased the stability and stiffness of the spine.Whereas,the reduced range of motion in different directions as well as axial displacement,increased stability index and enhanced stiffness varied among the groups.But in pair comparison,the difference was insignificant between Groups B and C and between Groups D and E (P ＞ 0.05).A significant difference was found in between Groups D and B,between Groups D and C,between Groups E and B and between Groups E and C (P ＜ 0.05).Conclusion Unilateral translaminar facet screw fixation combined with contralateral pedicle screw fixation + interbody cage fusion can be a favorable choice for bisegmental fixation and fusion of lumbar spine.
